Electrophotography is widely used in copiers, printers and printing machines, because, for example, a high-quality image is instantaneously obtained.
As for the electrophotographic photoreceptor (hereinafter, sometimes referred to as “photoreceptor”), which serves as the core of electrophotography, a photoreceptor using an organic photoconductive substance having advantages such as no pollution, ease of deposition, and ease of production is widely employed.
As the binder resin used for the electrophotographic photoreceptor, a bisphenol-A-polycarbonate has been conventionally used, but since the life (pot life) of the coating solution is short due to high crystallinity and the mechanical properties such as abrasion resistance are insufficient, this resin is scarcely used at present. Instead, it is a mainstream to use a specific polycarbonate such as bisphenol-Z-polycarbonate and bisphenol-C-polycarbonate, alone or by mixing it with other resins or copolymerizing it with other bisphenol components.
However, unlike bisphenol-A-polycarbonate, it is rare for such a specific polycarbonate to be widely used in other applications for general purposes, and therefore, the merit for mass production is small, giving rise to a drawback that the cost of the resin is very high. Furthermore, in using a binder resin for an electrophotographic photoreceptor, performances not required in other general-purpose applications, such as performance not impairing electrical characteristics, are generally required and the quality must be strictly checked for each production lot, which is disadvantageous in that the production by a large-scale continuous production system has a high risk and batch production at a relatively small scale is obliged.
Recently, in addition to bisphenol-A-polycarbonate, a polycarbonate resin obtained by copolymerizing a bisphenol component such as bisphenol A and a bisphenol component having an alkyl-substituted cycloalkyl component such as isophorone (see, Patent Document 1, hereinafter referred to as isophorone-based polycarbonate resin) is put into use in other applications for general purposes and is available at a relatively low cost. Moreover, this resin is soluble in an organic solvent used in the coating solution for the electrophotographic photoreceptor and has low crystallinity and therefore, the life of the coating solution is greatly improved as compared with bisphenol-A-polycarbonate.